The comma is the most common punctuation mark. Chances are if you look at a piece of your writing and you add up all the kinds of punctuation marks that you used, I'm willing to bet you that you used more commas then just about anything else. Commas and periods tend to be the most common. They're a few different ways to use the comma. It comes in handy in a lot of different scenarios.
And one of the most vital ways is that it can be used to separate 2 independent clauses in a sentence. An independent clause is basically a complete thought, so sometimes in one sentence you'll have 2 or more complete thoughts. And the comma is your friend in punctuating a sentence correctly. "He attended the class and the class proved tremendously helpful." In this sentence we have two complete thoughts. The first is, "He attended the class." That's a complete thought in and of itself and it could be its own sentence. And also, "and the class proved tremendously helpful."
Also, a complete thought. So, whenever you want to join 2 complete thoughts together in one sentence, you need what I call the comma conjunction, which means you put a comma and a conjunction. The conjunction can be a word like "and " in this instance, or "but" and now you have a complete sentence with he help of a comma. So, I hope that this gives you one useful way to use the comma in your writing.